1. Field of the Invention
The present invention relates to a novel cross-connector assembly for interconnecting a first and a second bracing member or rod, which are in relative opposition to each other. More particularly the present invention relates to a novel multi-directional articulating cross-connector assembly configured to be simultaneously articulated in four directions including to be rotated in-part so as to custom fit to and securely connect two relatively parallel-aligned spinal rods, which are positioned along the longitudinal axis of a subject's spinal column.
2. Background of the Technology
Spinal fixation apparatuses are widely employed in surgical processes for correcting spinal injuries and diseases. These apparatuses commonly employ longitudinal link rods secured to coupling elements and are secured to the bone such as vertebrae by spinal bone fixation fasteners such as pedicle screws, hooks and others. The opposing pair of longitudinal link rods are commonly disposed along the longitudinal axis of the spine and are held in position relative to one another by cross-connectors, also known as transverse connectors or transverse bridge elements.
As the technology of spinal surgery has developed and improved, each of the necessary spinal fixation components has also undergone improvements and modifications to address the short-comings of conventional spinal appliances. While some improvements have been made in the design and operation of cross-connectors for spinal rods, there remains an unfulfilled need for a cross-connector that provides simplicity of operation with a minimal number of parts, which can provide reliable, secure attachment of two spinal rods that due to the natural and variable contours of the subject's spine are seldom in a perfectly parallel disposition, one to the other.
To meet the problem of securely connecting two opposing spinal rods together, a requirement exists to provide a cross-connector that can easily be manipulated during surgery in four directions to include being rotated in-part about the longitudinal axis of the connector; that is, a device is required that can rotate around each of the three axis of the device and also be translated to shorten or lengthen the device along its longitudinal axis before being securely locked into the desired position. In addition, the connector should be configured to provide a low profile with the smoothest possible contoured external surfaces to avoid irritation of adjacent soft tissue and thus promote healing and comfort for the subject post surgery.
Conventional efforts to meet this need have fallen short of the desired cross-connector configuration. For example, U.S. Pat. No. 6,554,832, issued to Shluzas, as best seen in FIGS. 2 and 4 of that patent, provides a transverse connector, which includes first and second connector members for connection to the respective first and second spine rods. The two connector members are connected one to the other by a connecting rod, which can be withdrawn or extended in alignment with the longitudinal axis of the cross-connector for purpose of adjusting the length thereof. As shown in FIG. 2 of the Shluzas patent, the extent of movement of the connecting rod (Shluzas at 42) inwardly through the opening (40) is limited by the design of the device, which after allowing a limited amount of inward movement of the connecting rod will impede further inward movement when the connecting rod (Shluzas at 42) comes into contact with the inwardly disposed portion of the connecting member (Shluzas at 30), the spine rod (Shluzas at 12), or possibly the set screw (Shluzas at 34). The design of the Shluzas connector thus provides a very limited inward adjustment of the length of the device. The device of Shluzas is also configured such that the connecting rod can be pivoted about a pivot axis to adjust the azimuth of the axis of the first connector in relation to the axis of the second connector. That is, the Shluzas device allows the surgeon to pivot the connecting rod about a pivot axis thus allowing one end of the multi-part transverse connector to be pivotally adjusted away from the longitudinal axis of the other end of the connector either caudally or cephallicly in relation to the subject's spinal column. Importantly the pivoting movement of the Shluzas connector is limited to movement within the same horizontal plane relative to the longitudinal axis of the spinal cord. Thus, while the device of Shluzas does permit some limited adjustment in length and azimuth of the device, it is configured to structurally prohibit any upward or downward movement in relation to the surface plane of the spinal column. That is, the elevation of one end of the Shluzas connector relative to the other end of the connector cannot be adjusted. While the connector of Shluzas does provide some improvement over earlier such devices, it still falls short of the need to provide a connector that can simultaneously be configured to be rotationally adjustable about each of the three axis and translated along the length of its longitudinal axis. That is, the device of Shluzas cannot be adjusted in all three planes: length, azimuth, and elevation as well as be rotated in-part around the connector's longitudinal axis.
Thus a need exists for a cross-connector assembly that provides ease of operation by the surgeon to adjust one connecting end of the assembly in relation to the other end of the assembly by rotation of the device around each of the three axis and translated in length along the longitudinal axis, to securely lock the assembly in the selected configuration, and to provide a cross-connector that has a low profile and the smoothest possible external surface contours to promote healing and minimal irritation of adjacent soft tissues in the subject.